1. Field of the Invention
The present invention relates to an interference image determining method and an interference image determining apparatus utilizing the interference image determining method, and particularly relates to an interference image determining method utilizing the image characteristic of a caught current frame to update a defined interference image, and an interference image determining apparatus utilizing the interference image.
2. Description of the Prior Art
As related tech rapidly grows, the mouse utilizing a rolling ball or other apparatuses such as a tracking ball is replaced by an optical mouse or an optical touch control apparatus. Such optical mouse or optical touch control apparatus can be regarded as an optical replacement estimating apparatus, since these apparatuses determine a related displacement between a detecting surface of the apparatus and an object.
FIG. 1 is a schematic diagram illustrating a prior art optical displacement estimating apparatus 100, for determining displacement for a finger on a detecting surface. FIG. 1(a) illustrates a cross sectional view of the optical displacement estimating apparatus 100, and FIG. 1(b) illustrates a block diagram for a circuit controlling the operation for the optical displacement estimating apparatus 100. The optical displacement estimating apparatus 100 includes a detecting surface 103, a light source 105, a detector 107, lens 109, 111, a processing unit 113, a storage apparatus 115 and a light source controlling unit 117. The operation of the light source 105 is controlled by the light source controlling unit 117 and illuminates the finger 101 on the detecting surface 103 to generate in image. The detector 107 catches the frame in the image, and the processing unit 113 computes displacement of the finger 101 according to the caught frame. Also, the processing unit 113 controls data accessing of the storage apparatus 115 and the operation of the light source controlling unit 117.
However, some objects on the detecting surface 103, such as scraping trace, finger print or dust, may form an interference image in the caught frame such that the displacement estimation becomes un-accurate. Some related techniques are developed to solve these problems, but these techniques need extra hardware cost or complicated algorithm.